What do the light patterns on the HP LaserJet MFP M139e-M142e mean?

The printer uses different light patterns to indicate its status: a steady light indicates Ready, a blinking light indicates Processing, and other patterns indicate states such as Initializing/cleaning/cooling down, Cartridge error, Cartridge very low, or Error/manual feed/manual duplex/out of paper. If the light blinks fast, you can press the Start Copy/Resume button to continue printing or to print the information page. For a complete list of light patterns and display codes, refer to the user guide at hp.com/support. (Page 2)